Polymerization procedures for 2-pyrrolidone



United States Patent POLYMERIZATION PROCEDURES FOR Z-PYRROLIDONE Carl E. Barnes, Gloucester, William O. Ney, Jr., Providence, and William R. Nurnmy, Warren, R. 1., assignors, by mesnc assignments, to General Aniline & Film Corporation,,New York, N. Y.,-a corporation of Delaware No Drawing. Application February 24, 1953, Serial No. 338,552

Claims. .(Cl. 260-78) Thepresent invention relates to the polymerizationof.

five and sixmembered lactams, suchas pyrrolidone.

In the copending application of Barnes, Nummy and Ney, SerialNo. 260,558, filedDecember 7, 1951, now U. S. Patent No. 2,638,463 of May 12, 1953, there are described procedures :for polymerizing pyrrolidone and other five or six membered lactams using alkaline polymerization catalysts, .such as potassium hydroxide, potassium pyrrolidone andthe like. 'Theprincipal object of the present invention is to provide novel improvements in the polymerization procedures described in the above-mentionedpatent,

the disclosurse of which is hereby incorporatedin-and made, a part of the present application.

Arnore specific object of the invention-is the provision of procedures foripolymerizing pyrrolidone and-related lactamswhereby the rate of. the polymerization and yields the present invention,by virtue of'the discovery that acyl compounds, while not themselves .suitableas catalystsfor polymerizing. pyrrolidone and like lactams, .serve as activators, of the: alkaline polymerization catalyst usedaccording to the procedures described in the U. S. lPate'nt 2,638,463, thereby increasing the rate of polymerization and yield of polymers. 'It, has alsobeen noticed that these activators permit control of the molecular-Weight ofthe polymers.

As acyl compounds suitable for use according to the procedures of the invention; there may be-mentioned'acyl pyrrolidones, suchas-acetyl pyrrolidone, adipyl dipyrrolidone, stearoyl pyrrolidone, acetyl morpholone, acetyl piperidone; organic peroxides, such as benzoylperoxide; cyclic and non-cyclic anhydrides, such as maleic anhydride, pht-halic anhydride and acetic anhydride; la-ctones, such-as gammabutyrolactone, beta-propiolactone, gamma-valerolactone, delta valerolactone, and delta-caprolactone; lactide and glycollic lactide; alkyl esters'ofm-onoand di-carboxylic acids, such as butyl stearate, ethylacetatepropyl butyrate, propyl acetate, ethyl oxalate as well as esters of polyhydric alcohols, e. g. ethylene glycoldiacetate. =Pa-rticularly desirablefor use according to-the inventioniare the acyl pyrrolidones although any ofthe acyl compoundsmentioned above-will serve to activate the polymerization catalyst.

The catalysts that may be employed are, as mentioned above, those described in- United States Patent 2,638,463, i. ,e the alkali metals .such as sodium, potass ium and lithium, and the corresponding salts of these; metal s,,e., .g.,

the carbonates, as wen as hydroxides and oxides of the tion temperatures lie betweenO and. 200

.the mixture at temperatures pressures between 0.5 and 10 mm. .Therreaction'mixture the still pot is cooled, andallowed: to stand 2,809,958 PatentedQct. 1:5, 1957 2 alkali metals. In this'connecti-on, salts ofthe compound to be polymerized may be used as catalysts such as sodium orjpotassium or lithium pyrrolidone; In addition, the oxides andhydroxides of the alkaline earth metals, for example, calcium and barium, may be used as catalysts. Also,.organic metallic compounds, preferably those which are strongly basic may be used, such as thelithium, potassium and sodium alkyls, e. g., of the said alkali metals, such as sodium phenyl and sodium amide. i

The invention'herein described is'broadly applicable to the polymerization of fiveand six membered lactams as described in the above mentioned patent, including pyrrolidone, piperidone, morpholone, gamma-valerolactam, delta-valerolactam. The conditions. utilized forpolymerizing these materialsmay correspond with those outlinedin the above mentioned patent, except for'tiie addition of the acyl compound as activator.

The concentrationof the activator utilized shouldbe between .001% and 25% by weight of'the pyrrolidoneor otherlactam being polymerized. The mofstefiective concentrationrange lies between 2 and 10% by weight of the lactam although, in certain situations, for example, when an unusual effect is desired with respect to total yield'or molecular weight of the polymer, concentrates outside the range stated maybe used with advantage.

The concentrations recited in the preceding paragraph.

po meri ation nd i n use except for the additionof the according to'the invention,

imerQ Ym I zeti n Qat .d with those disclosed in activator, such as temperature,

lyst and the like, may correspon U. S. Patent No. 2,638,463. Thus, operable polymeriza- -C?" h preferred range lying'between 20 and 50 C. Bulk or mass polymerization may be utilized or, if desired, polymerization may reactive solvents such as dioxan and dimethyl 'formamide.

.In any event, whether solvents are or are not used, it is essentialthat the polymerization ,be carried out in the.

absence of water or any other material containing readily available proton. Otherwise,,the desired polymerization l e nh bite e p t -pres nce afa y a tivat The invention as described above is further-illustrated ath fo Q i a mpl Example 1 -done without the addition of activators.

Ina vessel equippedfor vacuum distillationand mechanical stirring thereis placed 200parts, of pyrrolidone, to which is added one part of potassium hydroxidepellets. The. waterformed is, removed by distilling. ofi20 parts of between.90 and .120 C., and

remaining. in for five days at room temperatureinavessel which-is sealed to exclude atmospheric moisture. The polymer -is isolated by the addition of 500 parts of distilled water and. is filtered off and. washed thoroughly; to rernove water Theyield of polymer; is -tiye parts or soluble. impurities. 2.5% ,and the polymer itself is of V CIY lGW lIlOlBCQIaI weight, as indicated by relative viscosity i et surements. .If

- a similar. -run,. carriedouton the sarne pyrrplidqne ii -the y same way, is allowed to stand for two weeks instead of five butyl lithium and the arylsbe carried out in solutions using non- Example 2 In a vacuum vessel is placed 200 parts of pyrrolidone, identical with that used in Example 1, and one part of KOH pellets. The water formed is removed by distilling off 20 parts of the mixture at temperatures between 90 and 120 C., and pressures between 0.5 and 10 mm. The reaction mixture remaining in the still pot is treated with 20 parts of gamma-butyrolactone, and the resulting mixture is allowed to stand at room temperature for two hours. By this time, the mixture has completely solidified and is treated with 500 parts of water, and the mixture thoroughly agitated to break up the relatively hard solid. The polymer is isolated as a nearly white powder by filtration and washed thoroughly with distilled water. 91 parts of polymer or a yield of 45.5% is obtained.

Example 3 In a vessel equipped for vacuum distillation and mechanical stirring are placed 200 parts of pyrrolidone identical with that used in Example 1 above, 20 parts of gamma-butyrolactone and one part potassium hydroxide pellets. 20 parts of this material is removed by distillation at temperatures between 90 and 120 C., at pressures of 0.5 to 10 mm. The reaction mixture remaining in the still pot is cooled and allowed to stand at room temperature. After standing three hours, the material is quite firm and solid. 500 parts of distilled water is then added and the mixture agitated thoroughly. The polymer obtained after filtration and thorough washing with distilled water amounts to 82 parts or 41 percent by weight.

Example 4 In a vessel equipped for vacuum distillation and mechanical stirring are placed 200 parts of pyrrolidone identical with that used in Example 1 above, and one part KOH pellets. 20 parts of this material is removed by distillation at temperatures between 90 and 120 C., at pressures of 0.5 to 10 mm. This material is allowed to stand for two weeks at room temperature in a vessel sealed to exclude atmospheric moisture. At the end of which time only a very small amount of polymer is present. To this mixture is added 20 parts of gammabutyrolactone. Within 15 minutes a noticeable thickening of the solution occurs, and at the end of 1 /2 hours, the material has solidified to a firm but workable solid mass. Upon treatment with 500 parts of distilled water, filtration and thorough water washing, 73 parts of 36.5 percent of polymer is obtained.

Example 5 In a vacuum vessel is identical C., and pressures between 0.5 to mm. The reaction mixture remaining in the still pot is treated with 20 parts of gamma butyrolactone, and the resulting mixture allowed to stand at room temperature for 24 hours. The polymerization proceeds to such an extent that the resulting solid is extremely hard and cannot be worked up by the addition of water, nor can it be readily shredded or cut. It is a very hard, tough, buff colored solid which has taken the shape of the container in which it stood. The polymerization is essentially complete within twenty-four hours.

Example 6 In a vessel equipped for vacuum distillation and mechanical stirring is placed 200 parts of pyrrolidone, identical with that used in Example 1, and one part of KOH pellets. The water formed is removed by distilling off twenty parts of the mixture at temperatures between and C., and pressures of between 0.5 and 10 mm. The reaction mixture remaining in the still pot is treated with one part of gamma-butyrolactone and allowed to stand for two weeks. The reaction mixture is set to a firm solid which can be readily disintegrated and to which 500 parts of water is added. The resulting mixture is thoroughly agitated, and the polymer is filtered off and washed with distilled Water. Forty-five parts or 22.5 percent yield of polymer is obtained.

Example 7 In a vacuum vessel is placed 200 parts pyrrolidone, identical with that used in Example 1, and one part KOH pellets. The water formed is removed by distilling off twenty parts of the mixture at temperatures between 90 and l20 C., and pressures of between 0.5 to 10 mm. One part of gamma-valerolactone is added and the resulting mixture is allowed to stand for three days at room temperatures. 500 parts of distilled water is added and the insoluble polymer filtered off and washed with distilled water. Forty-one parts of 20.5 percent of polymer is obtained which had comparatively high relative viscosity.

Example 8 In a vessel equipped for vacuum distillation and stirring, add 15 parts of KOH pellets while stirring to 1500 parts of pyrrolidone, seal the system and immediately distill off ca. 400 parts of pyrrolidone under vacuum as rapidly as possible (20 to 30 minutes). Pot temperatures should be less than 130 C., for best results; vapor temperatures will run 120 to C. Pressure will vary from about 10 mm. of mercury during the surge of released water in the early stages to less than 1 mm. at the end of distillation. This amount of distillate is desirable since it insures removal of nearly all the water present. The reaction mixture is then cooled to about 40 C., and 3.75 parts of adipyl dipyrrolidone dissolved in 100 parts of anhydrous pyrrolidone is stirred in. A mildly exothermic reaction sets in after a few will stop a laboratory stirrer.

After twenty-four hours standing, the tough gel is broken up and thoroughly agitated in a Waring blendor with about five volumes of Water to remove the remaining caustic and any other water soluble materials. The polymer is filtered and rewashed with about the same amount of water, filtered again, sucked dry at the pump and then dried in a circulating air oven at 65 to 7 C.

The yield after drying to less than 1% moisture is 468 parts of granular polymer or 39% conversion based on the 1200 parts of pyrrolidone in the polymerizing mixture. This polymer has a relative viscosity of 4.0

for .a 1% solution in meta cresol.

Example 9 Example 10 The procedure of Example 8 is repeated using 100 parts of butyl stearate as activator. After standing overnight, a very hard resinous mass is obtained. This mass is dissolved by warming in anhydrous formic acid and then reprecipitated by diluting with 10 volumes of water.

A 64% theoretical yield of product having a relative viscosity of a 1% solution in meta-cresol of 1.6 is obtained.

Example 11 100 parts of catalyzed pyrrolidone, as used in Example 7, is activated by the addition of 2 parts dimethyl malonate. A mildly exothermic reaction begins immediately. After standing for 48 hours, the reaction mixture sets and is worked up as described in Example 10. There are obtained 56 parts of polypyrrolidone.

Example 12 100 parts of catalyzed pyrrolidone, as used in Example 8, are activated by the addition of 2.2 parts benzoyl chloride. An exothermic reaction begins and, in less than one minute, a firm solid mass is obtained. After 48 hours, the mass is worked up in the manner of Example with formic acid. Yield of 74% polypyrroli done having a reactive viscosity of a 1 percent solution in meta-cresol of 6.7 is obtained.

As is apparent from the foregoing examples, the use of acyl compounds as activators in the polymerization of pyrrolidone and other five and six membered lactams according to the present invention, offers such advantages as increased yield of polymer and rate of polymerization.

Various modifications of the invention as described above will be apparent to those skilled in the art. Hence, it will be understood that the invention is not limited to the foregoing description except as it is defined in the appended claims.

We claim:

1. In the polymerization of Z-pyrrolido'ne using a polymerization catalyst selected from the group consisting of alkali metals, their salts, hydroxides, oxides and amides, alkaline earth metals and hydroxides and strongly basic organic metallic compounds, the improvement which comprises efiecting polymerization in the presence of an acyl activator each acyl radical of which is an acyl radical of a carboxylic acid and selecteed from the group consisting of organic acyl peroxides and carboxylic acid anhydrides, lactones, lactides, N-acyl derivatives of lactams, acyl halides and alcohol esters of carboxylic acids and wherein the concentration of said acyl activator is between 0.001% and 25% of the weight of said pyrrolidone being polymerized.

2. The process of claim 1 wherein the concentration of acyl activator is between 2 and 10% pyrrolidone being polymerized.

of the weight of 3. The process of claim 1 wherein the acyl activator is a lactone.

4. The process of claim organic acyl peroxide.

5. The process of claim 1 wherein the acyl activator is an alcohol ester of a carboxylic acid.

6. The process of claim 1 wherein the acyl activator is a carboxylic acid acyl derivative of pyrrolidone.

7. The process of claim 1 wherein the acyl activator is a carboxylic acid anhydride.

8. The process of homopolymerizing 2-pyrrolidone in the presence of a polymerization catalyst selected from the group consisting of alkali metals, their salts, hydroxides, oxides and amides, alkaline earth metals and hydroxides and strongly basic organic metallic compounds, comprising the steps of heating said pyrrolidone in the presence of said catalyst to remove water, cooling the resulting mixture from which water has been removed, adding as an acyl activator each acyl radical of which is an acyl radical of a carboxylic acid, said activator being a compound selected from the group consisting of organic acyl peroxides, carboxylic acid anhydrides, lactones, lactides, N-acyl derivatives of lactams, acyl halides and alcohol esters of carboxylic acids, and thereafter allowing polymerization of the cooled mixture to continue at a temperature of between 20 C. and C. and wherein the concentration of the acyl activator is between .001% and 25% of the weight of pyrrolidone being polymerized. 9. The process of claim 8 in which the acyl activator is a carboxylic acid anhydride.

10. The process of claim 8 wherein 1 wherein the activator is an the heating is carried out at a temperature between and C. under reduced pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,251,519 Joyce et al Aug. 5, 1941 2,638,463 Ney et al May 12, 1953 OTHER REFERENCES Schildknecht: Vinyl and Related Polymers, Wiley, 1952, pages 664-666. 

1. IN THE POLYMERIZATION OF 2-PYRROLIDONE USING A POLYMERIZATION CATALYST SELECTED FROM THE GROUP CONSISTING OF ALKALI METALS, THEIR SALTS, HYDROXIDES, OXIDES AND AMIDES, ALKALINE EARTH METALS AND HYDROXIDES AND STRONGLY BASIC ORGANIC METALLIC COMPOUNDS, THE IMPROVEMENT WHICH COMPRISES EFFECTING POLYMERIZATION IN THE PRESENCE OF AN ACYL ACTIVATOR EACH ACYL RADICAL OF WHICH IS AN ACYL RADICAL OF A CARBOXYLIC ACID AND SELECTED FROM THE GROUP CONSISTING OF ORGANIC ACYL PEROXIDES AND CARBOXYLIC ACID ANHYDRIDES, LACTONES, LACTIDES, N-ACYL DERIVATIVES OF LACTAMS, ACYL HALIDES AND ALCOHOL ESTERES OF CARBOXYLIC ACIDS AND WHEREIN THE CONCENTRATION OF SAID ACYL ACTIVATOR IS BETWEEN 0.001% AND 25% OF THE WEIGHT OF SAID PYRROLIDONE BEING POLYMERIZED. 